Fork-shaped one-piece electrical spring contacts

ABSTRACT

An electrical contact folded from one piece of conductive sheet having sets of fork shaped contact finger projecting from the folded body. A projecting tongue located between fingers on one side of the body engaged with projections on the other side of the body holding the folded body portions juxtaposed.

United States Patent Grenda [54] FORK-SHAPED ONE-PIECE ELECTRICAL SPRING CONTACTS Hans August Herbert Grenda, D- 7758 Meersburg, Germany Assignee: W. Holler 8: Co. KG, Meersburg,

Bodensee, Germany Filed: March 29, 1971 Appl. No.: 128,840

inventor:

Foreign Application Priority Data March 28, 1970 Germany ..G 70 11 611.9

US. Cl. ..339/258, 29/629, 113/119 Int. Cl. ..H01r 11/22 Field of Search ..339/176, 217, 258, 259, 276,

References Cited UNITED STATES PATENTS 9/1963 MacNamara ..339/217S [451 Dec. 19, 1972 Kent Catalog No. 121206, 1958-2, 339-276F Primary Examiner-Marvin A. Champion Assistant Examiner-William F. Pate, I11 Attorney-Watson, Cole, Grindle & Watson [5 7] ABSTRACT An electrical contact folded from one piece of conductive sheet having sets of fork shaped contact finger projecting from the folded body. A projecting tongue located between fingers on one side of the body engaged ,with projections on the other side of the body holding the folded body portions juxtaposed.

8 Claims, 3 Drawing Figures PATENTEDBEB 1 I912 3. 706; 960

INVENTORI FORK-SHAPED ONE-PIECE ELECTRICAL SPRING CONTACTS The innovation relates to a fork-shaped contact spring, especially for printed circuit boards, to squeeze against the electric conductors and with contact fingers made of double the material thickness, which develops by folding an essentially symmetrical punched part.

Fork-shaped contact springs whose thickness of material develops by folding essentially symmetrical punched parts have been known. Thus, for example, in German Utility Patent No. 1,998,543, a contact spring strip is proposed, in which the individual contact springs are produced in one piece from a single metal element, especially a punched element, representing the two contact elements each time in a homologous arrangement, which strip is folded along the plane of symmetry reflecting the contact elements. One drawback of the individual contact springs of the spring strip is that the two resilient arms producing the contact giving spring pressure consist in each instance of two individual elements. Other contact springs have already become known which are made from only a single punched element. The parts which are placed on top of one another during the manufacturing process rise up again during the succeeding processing steps and strike against the processing devices, so that the entire spring may break off the band-shaped starting material. Furthermore, these known contact springs have the disadvantage that, when used as individual contacts, they are inclined to twist as soon as they are placed on a printed circuit board, since actually they rest only in a punctiform manner on the paths of the conductors.

It is the object of the invention to create a forkshaped contact spring which is suitable for use in contact housings, for example contact strips, which can be made easily and with the least possible production waste and which, beyond that, has great stability; in addition, the contact springis to be in a position to conduct considerable currents as switched, forexample, in electric household appliances. Furthermore, the contact spring is to be built in such a way that-used as an individual spring-it will sit securely on a printed circuit board and will not be able to twist. it should be possible to attach, electrically as well as mechanically, cables to the contact spring with the aid of a simple squeeze connection. According to the innovation, the

above mentioned tasks will be achieved by the contact fingers, which either are opposite or beside one another, each time being bent in the opposite rotational direction by 90 around their longitudinal axis as compared to the flat material.

According to one feature of the invention, two contact parts, which are independent per se and which are part of the symmetrical punched element, are held together in their folded state by a tongue.

According to a further feature of the invention, the tongue simultaneously serves to arrest the contact spring in a housing, for example, in a plug socket.

An effective feature of the invention is that, the tongue will be prevented from bending back by means of shoulders which have been attached to one of the contact elements.

Yet another feature of the invention provides that the attaching flange for the cable is attached in the plugging direction.

According to a still further feature of the invention, the attaching flange is at an angle with respect to the plugging direction.

As compared to known contact springs the invention has several advantages. By folding two per se independent contact elements belonging to one single punched part and by twisting the contact fingers, four points of support will result on the printed circuit board. As a result of that, a very secure seat will be achieved, so that any kind of twisting of the contact spring is impossible. After the free punching of the punched element and after the folding of the two contact elements, by the proper bending of a tongue the two contact elements will be placed one on top of the other so that they cannot separate. Consequently, during the subsequent finishing process, no parts of the contact spring will project essentially beyond the plane extending through the bending line to strike against thefinishing installation. Furthermore, an advantage of the invention is that the tongue serving to hold together the two parts serves atthe same time as a stop for the contact spring in a contact housing.

The innovation will be explained onthe basis of an embodiment given by way of example and with the help of a drawing.

In the drawing:

FIG. 1 shows a top view of the punched part,

FIG. 2 shows a top view of the punched part during punching from a band-shaped starting material,

FIG. 3 shows a perspective view of a completed forkshaped contact'spring.

It can be seen from FIG. 1 that for the production of a fork-shaped contact spring according to the invention, a punched part is used-if flange 6 is disregarded-consisting essentially of two independent contact springs 10, 11, which together form an almost symmetrical punched element. One contact element in this case has been provided additionally with tongue 8 and the other contact element with projections 9. During the next processing step, both contact parts are folded at a bending line 5 into a single contact spring. The second contact element 10' could also be attached in such a way to the first contact element 1 1 that it can be placed on top of contact element 11 along a bending line 5.

As soon as, for example, the two contact elements 1 l and 10 have been folded on top of one another, tongue 8 is bent over in such a way that it will hold contact element 10 on contact element 11, so that it can no longer return. In order to secure tongue 8, projections 9 can be provided on the second contact element 10, between which a space will remain free which is smaller than the width of tongue 8. Therefore, as soon as tongue 8 holds the contact element 10 on contact element 11, the projections 9 can again be bent in the direction toward the plane formed by theflat material until the projections abut against tongue 8. From that time on,

l060ll 0749 will be obtained for both sides of an areal contact, for example, a printed circuit board (FIG. 3).

The free end of tongue 8 (FIG. 3) is bent out from the plane determined by the flat material and, as a result of that, it serves to stop a contact spring inserted into a contact housing, for example, a spring-contact strip. Consequently, the contact spring will be prevented from falling out of the contact housing.

The flange 6 (FIG. 1), which has been attached essentially symmetrically to the punched element, serves in a manner known per se for an electrical or mechanical attachment of cables. As can be seen from FIG. 2, the flange 6 can be attached just as well in the pluggingin direction to the symmetrical punched element. Naturally, in the case of all embodiments, flange 6 is a component of the punched element. In FIG. 2 it has been shown moreover how the punched-elements can be punched out from a flat starting material 7. Naturally, it will also be possible that the punched elements shown in FIG. 2 assume a position on the band-shaped starting material which is twisted by about 90.

What is claimed is:

l. A one-piece electrical contact formed from a blank of sheet material, said blank comprising:

first and second contact elements for folding in overlapping relationship with one another about a first axis between said first and second contact elements; said first contact element including first and second contact fingers symmetrically disposed with respect to a second axis extending between said first and second contact fingers for folding into a plane substantially normal .to the plane of said sheet material; said second contact element including third and fourth contact fingers symmetrically disposed with respect to a third axis extending between said third and fourth fingers for folding into a plane substantially normal to the plane of said sheet material, a tongue extending between said third and fourth contact fingers for holding said first and second contact elements in closely abutting overlapping relationship;

said first and third contact fingers and said second and fourth contact fingers are respectively symmetrically positioned with respect to said first axis; and

a flange element for forming a connector to receive an electrical conductor.

2. The structure as in claim 1 wherein said second and third axes are co-linear.

3. The structure as in claim 1 wherein said second and third axes are in spaced parallel relationship to one another.

i 4. The structure as in claim 2 wherein said first contact element further includes first and second projec-. tions symmetrically formed with respect to said second axis and the respective free ends thereof are spaced a distance less than the width of said tongue to form an aperture for retaining said tongue.

5. The structure as in claim 3 wherein said first contact element further includes first and second projections symmetrically formed with respect to said second axis and the respective free ends thereof are spaced a distance less than the width of said tongue to form an a erture for retainin said ton ue.

6. A one-piece ele ctrical c ntact of the fork-shaped contact type, comprising:

first and second contact elements folded in overlapping relationship with one another about a first axis between said first and second contact elements;

said first contact element including first and second planar contact fingers symmetrically disposed with respect to a second axis extending between said first and second contact fingers, the respective surfaces of said first and second contact fingers extend substantially normal to the plane'of said first and second contact elements;

said second contact element including planar third and fourth contact fingers symmetrically disposed with respect to said second axis, the surfaces of said third and fourth contact fingers extend substantially substantially normal to the plane of said first and second contact elements, whereby said first and second and said third and fourth contact fingers are respectively aligned to form opposing arms of said fork-shaped contact, a tongue extending between said opposing arms and overlapping said first contact element for holding said first and second contact elements in said overlapping relationship; and

a flange element formed into a connector to receive an electrical conductor.

7. An electrical contact as in claim 6 wherein said first connector element further includes first and second projections symmetrically formed with respect to said second axis and the respective free ends thereof are spaced a distance less than the width of said tongue to form an aperture for retaining said tongue.

8. An electrical contact as in claim 7 wherein said respective free ends are folded into engagement with said tongue.

II I l 

1. A one-piece electrical contact formed from a blank of sheet material, said blank comprising: first and second contact elements for folding in overlapping relationship with one another about a first axis between said first and second contact elements; said first contact element including first and second contact fingers symmetrically disposed with respect to a second axis extending between said first and second contact fingers for folding into a plane substantially normal to the plane of said sheet material; said second contact element including third and fourth contact fingers symmetrically disposed with respect to a third axis extending between said third and fourth fingers for folding into a plane substantially normal to the plane of said sheet material, a tongue extending between said third and fourth contact fingers for holding said first and second contact elements in closely abutting overlapping relationship; said first and third contact fingers and said second and fourth contact fingers are respectively symmetrically positioned with respect to said first axis; and a flange element for forming a connector to receive an electrical conductor.
 2. The structure as in claim 1 wherein said second and third axes are co-linear.
 3. The structure as in claim 1 wherein said second and third axes are in spaced parallel relationship to one another.
 4. The structure as in claim 2 wherein said first contact element further includes first and second projections symmetrically formed with respect to said second axis and the respective free ends thereof are spaced a distance less than the width of said tongue to form an aperture for retaining said tongue.
 5. The structure as in claim 3 wherein said first contact element further includes first and second projections symmetrically formed with respect to said second axis and the respective free ends thereof are spaced a distance less than the width of said tongue to form an aperture for retaining said tongue.
 6. A one-piece electrical contact of the fork-shaped contact type, comprising: first and second contact elements folded in overlapping relationship with one another about a first axis between said first and second contact elements; said first contact element including first and second planar contact fingers symmetrically disposed with respect to a second axis extending between said first and second contact fingers, the respective surfaces of said first and second contact fingers extend substantially normal to the plane of said first and second contact elements; said second contact element including planar third and fourth contact fingers symmetrically disposed with respect to said second axis, the surfaces of said third and fourth contact fingers extend substantially substantially normal to the plane of said first and second contact elements, whereby said first and second and said third and fourth contact fingers are respectively aligned to form opposing arms of said fork-shaped contact, a tongue extending between said opposing arms and overlapping said first contact element for holding said first and second contact elements in said overlapping relationship; and a flange element formEd into a connector to receive an electrical conductor.
 7. An electrical contact as in claim 6 wherein said first connector element further includes first and second projections symmetrically formed with respect to said second axis and the respective free ends thereof are spaced a distance less than the width of said tongue to form an aperture for retaining said tongue.
 8. An electrical contact as in claim 7 wherein said respective free ends are folded into engagement with said tongue. 